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  1. Core Server
  2. SERVER-90871

Document::getNestedFieldNonCaching returns incorrect result

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    • Type: Icon: Bug Bug
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 8.0.0-rc7
    • Affects Version/s: None
    • Component/s: None
    • Query Execution
    • Fully Compatible
    • ALL
    • v8.0
    • 200

      Minimal reproduction script:

      db.coll.drop();
assert.commandWorked(db.coll.insertMany([
    {_id: 1, "obj": {"obj": {} } },
    {_id: 2 },
]));
const result = db.coll.aggregate([{$addFields: {"obj": null}}, {$sort: {"obj.obj": 1, _id: 1}}]).toArray();
jsTestLog(result);

      Incorrect result:

      [jsTest] ----
[jsTest] [ { "_id" : 2, "obj" : null }, { "_id" : 1, "obj" : null } ]
[jsTest] ----

      Note that the order of returned documents is wrong. The document is marked as modified after passing the $addFields stage. The top-level "obj" field is in the document cache. Document::getNestedFieldNonCachingHelper function ignores the cache and returns the "obj.obj" field in the backing BSON.

            Assignee:
            rui.liu@mongodb.com Rui Liu
            Reporter:
            rui.liu@mongodb.com Rui Liu
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            Watchers:
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              Created:
              Updated:
              Resolved: